The present invention is based on a device for the control of a throttle diameter for a line carrying fuel for an internal combustion engine. Such a device is already known which, however, has the disadvantage that because (due to reasons of production requirements and functional necessities) the radial gap is not kept sufficiently narrow or tight while in a closed condition of the device, leakage problems arise so that even in the closed state of the device an undesireable leaking flow of the fuel occurs.